The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.
TV viewers can record broadcasted TV programs using a videocassette recorder (VCR). As such, a VCR user can record a particular TV program at the time it is broadcasted and play back the same recorded TV program at a later time. In order to accomplish this, a VCR changes the electrical signals representing a TV program into magnetic signals and stores the magnetic signals on a magnetic tape. The magnetic tape is usually in the form of a videocassette tape inserted into the VCR by the VCR user. When a VCR user decides to play back the TV program, the process is reversed, and the VCR changes the magnetic signals stored on the videocassette tape into electrical signals and sends the electrical signals to a TV set.
With the development of digital technology, VCRs are being replaced by digital video recorders (DVRs). A DVR records broadcasted TV programs for later playback by changing electrical signals of the TV program into digital information and storing the digital information on a hard drive. When a user plays back the recorded TV program, the DVR converts the digital information back to analog signals and sends the signals to the TV set which displays the TV program for the viewer. Also, with the advent of digital TVs, the DVR can receive digital and analog signals and send digital signals directly to a digital TV set which displays the TV program in digital form. Many content providers now use digital cable and satellite technology to broadcast digital programming. The digital programming is received by cable boxes and/or satellite transceivers which are used to displayed the digital programming to a user on a display screen. DVRs thus have the ability to receive digital programming signals from cable boxes or satellite transceivers for recording and display as well as being incorporated into such devices.
DVRs have become increasingly popular and widely used for recording TV programs. More importantly, the use of DVRs for recording TV programs has caused content providers to search for different means of presenting content to DVR users and enriching the experience of video programs. Customized broadcast content has been lacking in the content provider and DVR communities. U.S. patent application Ser. No. 09/665,921 owned by the Applicant, describes a method for tagging broadcast content using the closed caption area. U.S. Pat. No. 6,233,389, owned by the Applicant, also describes a method for recognizing specific words in the closed caption data. A technique for recognizing distinct events within an unmodified video program is desirable.